Bullet with booster filling and its manufacture

ABSTRACT

A bullet having a cavity in its forward end that is open at that end and a filling situated within said cavity. Preferably, the filling comprises an elastomer. Preferably, the elastomer filling is vulcanized. More preferably, the vulcanized elastomer filling has a Shore hardness in the range from about 6 to about 90. Alternatively, the filling is a colored rigid polymer filling, if a non-expanding training hollow point bullet is desired. In particular, the invention is a filling and its application to hollow point bullets for the purposes of: improving bullet expansion during the penetration of liquid targets; preventing clogging with debris from intermediate targets; increasing expansion during the perforation of hard materials; preventing the expansion of training bullets; and allowing users to identify different cartridge designs. The invention is also devices and methods for introducing the filling into the cavity.

This application claims the benefit of U.S. Provisional Application No. 60/367,843 filed on Mar. 25, 2002 and U.S. Provisional Application No. 60/432,492 filed on and Dec. 10, 2002; the disclosures of which applications are incorporated by reference as if fully set forth herein.

TECHNICAL FIELD

This invention relates to improvements to bullets having an open, forward end cavity, including hollow point bullets. In particular, the invention relates to a filling to be applied to the cavity of a hollow point bullet for the purpose of improving, hastening and assuring its expansion and other purposes and to devices and methods for introducing the filling into the cavity.

BACKGROUND ART

In this document, these terms are defined as follows:

-   -   TARGET: The desired place of impact of a bullet.     -   LIQUID TARGET: A target that behaves like a liquid having a         density of 1.0, such as 10 percent gelatin or human soft         tissues.     -   INTERMEDIATE BARRIERS: Materials interposed between the gun and         the target that must be perforated if the bullet is to strike         the target.

For defense purposes, bullet efficiency is measured by the probability that a bullet's impact will stop an aggressive behaviour and is called “stopping power.” Stopping power is strongly related, to the pressure intensity generated by the bullet when it strikes its target. Pressure wave intensity depends, in turn, on the maximum bullet diameter achieved during expansion and the square of the velocity at the moment of maximum expansion.

Because high striking velocities can be attained only with long-barrelled guns, like rifles, efforts have been directed toward improve the efficiency of ammunition fired with portable short-barrelled guns, like pistols and revolvers, that cannot achieve high striking velocities. The practical way to improve the efficiency of these weapons is to employ bullets that increase in diameter during penetration of the target.

As illustrated in FIGS. 1, 2 and 3, one solution to this problem that is taught in the background art is to employ soft lead bullet 12 (see FIG. 1) or a bullet with soft lead tip 14 and bullet jacket 24 (see FIGS. 2 and 3). Pure lead is quite soft and has yield strength of about 1.6 kilogram per square millimetre (k/mm²). This approach requires a striking velocity above 410 meters per second (m/sec) to expand a lead bullet. As illustrated in FIG. 4, a plain lead bullet or one with a soft lead tip expands in a mushroom shape 164.

The body of a human or an animal is heterogeneous but is composed mostly of water and can be considered a liquid target. High velocity bullets fired into liquids like water or living tissue are severely distorted. It is evident that the liquid resistance to penetration, related to the stagnation pressure has a significant effect on the shape of the bullet. Media like gelatin blocks are employed as targets during testing to simulate living tissues.

When a bullet penetrates a liquid mass at high velocity, the liquid flows around the bullet nose creating pressures that vary with location and that reach a maximum value in what is called stagnation area. This area is that part of the bullet forward surface that is perpendicular to the direction of movement. The pressure at this point is called the stagnation pressure. As is illustrated in FIG. 9, stagnation pressure is related to the square of the bullet's velocity. Hand gun bullets have velocities ranging from 300 to 450 m/sec, corresponding to stagnant pressures from 500 to 1,000 kg/cm². This phenomenon is responsible for bullet deformation.

To increase the amount of bullet deformation, the hollow point bullet has been devised. A number of background art designs for hollow point bullets are illustrated in FIGS. 5-12. One approach is to use a drill to produce cavity 20 having an open, forward end in the nose of a conventional (plain) bullet, as illustrated in FIG. 5. Cavity shape may vary according to the bullet design. Some hollow point bullets are made with pure lead, as illustrated in FIGS. 5, 7 and 10, with cavity 20 having an open, forward end at the nose and closed cavity end 30 at the rear end of the cavity. These bullets require lower velocities than soft point bullets to achieve larger expansions. Most hollow point bullets (see FIGS. 11 and 12) comprise jacket 24 and require (FIG. 12) a higher velocity and slits 74 formed in the nose portion 28 to expand.

Pascal's principle states that, in a liquid at rest in a closed container, a pressure change in one part of the liquid is transmitted without loss to every other part of the liquid and to the walls of the container. A hollow point bullet with an open, forward-end cavity is not a closed container. Only when the hollow point bullet strikes a liquid target at high velocity, does the liquid penetrate with high pressure into the open, forward end of the cavity transmitting the pressure to the walls of the cavity, in accordance with Pascal's principle.

FIG. 16 illustrates the progressive expansion of hollow point bullet 40 as it penetrates liquid target 38. In this example, the velocity at which bullet 40 strikes target 38 is about 350 m/sec. This is a typical handgun bullet velocity.

At initial position 44, bullet 40, with its hollow point cavity 20 empty, is about to strike target 38. Because of the bullet's high velocity and the inertia of the liquid molecules of target 38, bullet 40 must travel a certain distance and reach cavity filling completed position 46 before cavity 20 is completely filled with the liquid of target 38. Only when cavity 20 is filled is the stagnation pressure on the bullet tip transmitted throughout the liquid inside cavity 20 and is applied to the walls of cavity 20, starting expansion at expansion initiation position 48.

Once cavity 20 is filled at cavity filling complete position 46, and because of the inertia of the material of which bullet 40 is made, bullet 40 must travel about ten mm more through target 38 to expansion initiation position 48 before the walls of cavity 20 begin to expand radially and the expanded area is simultaneously bent backward by target axial pressure 62. Expansion of bullet 40 continues at continuing expansion position 50 after a total travel about eighty mm through target 38. By this position, the forward end of bullet 40 has been transformed into ring 56 with the metal at its outer diameter bent backward. The maximum diameter that occurs seldom reaches seventy percent larger than the original caliber. By this position, the velocity of bullet 40 has been reduced by about twenty percent to about 280 m/sec and the pressure wave intensity, which is related to the stagnation pressure and maximum expanded ring diameter, has reached its maximum value. Passing through maximum expansion position 52, bullet 40 continues to penetrate target 38, without further deformation, until its velocity drops to zero.

For a given velocity, the larger the expansion achieved by bullet 40, the lower the penetration achieved by bullet 40, because these phenomena are antagonistic. For example, for a conventional 9 mm hollow point bullet, the average maximum expansion achieved in testing media is about sixteen mm and the penetration is about 300 mm. If expansion is reduced, for example to twelve mm, stopping power is also reduced but penetration increases to 500 mm.

Some police forces require ammunition with a high stopping power (which increases with larger expansion) and deep penetration (which decreases with larger expansion). What is needed is a bullet that fulfils these requirements.

Much deeper penetration with larger expansion can be achieved with hollow point bullets by increasing the striking velocity above 400 m/sec. In that penetration in liquids is a logarithmic function of velocity, small increases in velocity (from 350 to 410 m/sec) do not effectively increase penetration. The observed penetration increase is due to other reasons. With velocities above 400 m/sec, the bullet's expanded area after reaching its maximum diameter is reduced by fractures, leaving a stump which has a diameter close to the original calibre and about eighty percent of the original mass. It is the stump that achieves deeper penetration. Stopping power is related to the maximum pressure wave intensity, even if it only lasts a few microseconds (1/1,000,000 of a second). Thus, it does not matter that, after expanding, the bullet fractures and its expanded area is reduced.

This mechanism explains the success (in terms of stopping power) of hollow point 357 calibre magnum bullets. The velocity of these bullets is about 430 m/sec, which insures a large expansion and a subsequent fragmentation of the expanded ring. Velocities as high as this are very difficult to achieve in calibres other than magnums. What is lacking in the background art is an approach that causes the bullet to expand sufficiently to achieve the fracture, combining high stopping power with deep penetration, but at much lower velocities than are possible with magnum calibres.

The degree of expansion of hollow point bullet 40 also depends on how completely the liquid of target 38 fills cavity 20. If cavity 20 is not completely filled, hollow point bullet 40 does not expand.

In police applications, very often a bullet must perforate what are called “intermediate barriers” before striking the target. Typical intermediate barriers are car doors or windshields, wood door panels, gypsum construction panels, and leather objects like a belt or heavy clothing such as is worn in winter. Today, this is so important that most handgun ammunition evaluations carried out by police forces measure bullet performance only after the bullet has penetrated an intermediate barrier.

If hollow point bullet 40 penetrates an intermediates barrier such as (such as wood, textiles, leather or gypsum) before striking final target 38, cavity 20 can fill with debris associated with penetrating the intermediate barrier that prevents cavity 20 from being filled with the liquid of target 38. Under these conditions, the bullet does not expand, defeating the purpose of the hollow point.

If hollow point bullet 40 penetrates an intermediates barrier such as a thin plate metal as is encountered in car doors or metallic furniture, the hollow point nose will be riveted, closing the cavity and also defeating the purpose of the hollow point. Intermediates barriers such as wood, textiles, leather or gypsum, are easily perforated by hand gun bullets, as their thickness and resistance are low. However, hollow points are easily filled by the barrier's material. In these cases, the bullet does not expand and behaves as an undeformable bullet. Stopping power is reduced and penetration in liquid targets or tissue simulants increase to unacceptable values. What is needed is a filling for the hollow point cavity so it cannot be filled by debris so that its performance remain unchanged after perforating barriers such as wood, textiles, leather or gypsum.

Metal plates offer a different kind of problem to hollow point bullets. In this regard, metal plates are classified at “thin” or “thick.” A thin metal plate is one that can be perforated by a bullet. A thick plate is one that cannot be perforated. For hand gun ammunition, a thin (mild steel) plate is a No. 20 plate, which is about 0.9 mm thick, or a 2 mm thick hard aluminium alloy.

A thick plate is a No. 12 steel plate, which is 2.8 mm thick. This distinction is made because the effect of the bullet on the plate, and the effect of the plate on the bullet, interact continuously during the whole perforation process and are entirely different depending on whether perforation occurs or not.

A thick plate impacted by a bullet suffers only elastic deformation, and the bullet is squashed. If the kinetic energy of the bullet is sufficiently high, heat generated by this deformation melts the lead and the bullet disintegrates. If the bullet is jacketed, only the jacket is recovered.

Perforation of a thin plate by a high velocity bullet is illustrated in FIG. 18. Thin plate 106 is a two mm thick aluminium plate that better shows the side deformation and fracture of bulge 112 than a 0.9 mm steel plate. When plain bullet 108 strikes thin plate barrier 106 at average hand gun velocities (300 to 450 m/sec), plate 106 is stretched, forming initial bulge 112 while the bullet's tip is riveted, copying the shape of bulge 112, and increasing the bullet's diameter. Both deformations are simultaneous. The higher the bullet's velocity, the smaller the bulge, and the riveted bullet diameter, is. Sides 116 of bulge 112 are stretched becoming thinner at thinner side 114. When the tension at thinner side 114 exceeds the material's resistance, circular crack or fracture 120 is produced. Fractured cap 122 has a smaller diameter than the bullet and adheres to the tip of riveted bullet 110. The diameter of hole 118 is enlarged as the bullet passes through. Hole 118 is clean with a sharp edge and has a larger diameter than fractured cap 122. As the bulging contains and limits the bullet's riveting, high velocity bullets expand very little while perforating thin metal plates.

The first stages of perforation of thin plate 106 by high velocity hollow point bullet 40 are illustrated in FIG. 19. The bullet is riveted like plain bullet to produce hollow point bullet with riveted nose 124. Cavity 20 disappears. As hollow point bullet 40 is lighter but has the same volume as plain bullet 108, the length of hollow point bullet with riveted nose 124 is slightly shorter. Because a hollow point bullet has a softer nose than a bullet with a full metal jacket, the riveted diameter is about ten percent larger and the capacity to perforate a thin metal plate is reduced. With the same kinetic energy, a 9mm full metal jacket bullet can perforate six plates expanding its diameter progressively as successive plates are perforated and reaching a maximum diameter of twelve mm. A conventional Silver Tip® hollow point bullet expands from twelve mm after perforating the first plate to fourteen mm after the last, doubling its average frontal surface area and perforating only three plates.

Perforation of steel thin plate 106 by a low velocity plain bullet 108 is illustrated in FIG. 21. When striking velocities are low, e.g., around 250 m/sec, large diameter bulge 132 is produced, which is shallow but the deformed area is of plate 106 is several times the diameter of deformed bullet 131, forming a shallow cone. As the shallow bulge does not restrain the riveting of the bullet, deformed bullet 131 is riveted to a larger diameter than is the case when velocities are high. Perforation is less efficient as more energy is spent to deform deformed bullet 131 and plate 106. As the depth of large diameter bulge 132 increases, radial cracks 134 are produced at the tip of the bulge. Deformed bullet 131 passes through the cracks, pushing aside the metal to produce irregular perforation 136 (which is called petalling).

For training purposes, there is a need for non-expanding bullets that have the same external ballistic features and that insure the same point of impact as currently-employed expanding hollow point bullets. Because a particular hollow point bullet can be designed to have different features (such as the degree of bullet expansion, bullet velocity, target penetration), and because the external appearance of different cartridges (i.e., the bullet assembled into the case) can be indistinguishable, there is a need to provide users with a way to easily differentiate among different cartridges.

The background art is characterized by U.S. Pat. Nos. 219,840; 3,348,486; 3,357,357; 3,911,820; 4,338,862; 4,550,662; 4,947,755; 5,208,424; 5,365,853; 5,454,325; 5,763,819; 5,943,749; 6,115,894; 6,115,894; 6,176,186; 6,178,890; 6,305,290; 6,305,292; the disclosures of which patents are incorporated by reference as if fully set forth herein. A description of the limitations of the background art is presented below.

As illustrated in FIGS. 5 and 10, the first hollow point bullets were made of lead, were unjacketed and were provided with cavity 20 having an open forward end at the tip. U.S. Pat. No. 219,840 issued in 1879 to Winchester does not disclose a hollow point bullet per se, but it does disclose a device for manufacturing hollow point lead bullets similar to the example shown in FIG. 10.

From 1882 to 1898, British colonial forces employed a .455 calibre revolver that fired lead bullets having a hemispherical hollow point cavity 22, as illustrated in FIG. 7. These bullets were called “Man Stoppers.” In spite of their very low velocity of about 180 m/sec, the bullets expanded by sixty percent (see FIG. 8) after striking a liquid target.

FIGS. 10 through 12 illustrate several common handgun hollow point bullets that can be improved in accordance with the techniques disclosed herein. FIG. 10 presents a conventional, full-lead hollow-point bullet without a case. To prevent barrel fouling with lead, bullets of this type may be either copper clad or coated with Nylon® or Teflon®.

FIGS. 11 and 12 show conventional jacketed hollow point bullets. Jacket 24 is made thinner in nose region 28, and slits 74 are formed at the bullet's nose to allow jacket 24 to shred during expansion of the bullet according to U.S. Pat. No. 4,193,348 that was issued to Halverston in 1978. This successful design is market by Olin under the trademark Silver Tip®. In this design, cavity 20 is relatively small and jacket 24 is thinner in nose region 28. Axial slits 74 are formed in jacket 24 at the bullet's nose. As illustrated in U.S. Pat. No. 5,208,224, jacket 24 lines cavity 20.

FIG. 14 shows a background art design that is disclosed in U.S. Pat. No. 5,943,749. In this design, jacket 24 forms cavity 4. In several U.S. patents, including U.S. Pat. Nos. 4,550,662; 4,947,755 and 5,763,819; the cavity is tapered to a conical shape.

U.S. Pat. No. 3,881,421 that was issued to Burczynski disclosed to a very successful ammunition marketed under the trademark Hydrashock®). The cavity includes a conical central post. Hydrashock® bullets are produced with and without jackets and have a very high expansion ratio. The effects of the central post on expansion and accuracy were evaluated by the FBI in 1990, comparing the effects of identical bullets with and without the central post. The conclusion was that the central post slightly improved the bullet's performance (WWW domain firearmstactical.com.briefs26htm).

FIG. 13 shows a bullet design called Rhino-Ammo, which is not patented but is disclosed in the background art section of U.S. Pat. No. 5,763,819 (col. 5, lines 1-12) and U.S. Pat. No. 6,115,894 (col. 5, lines 21-35). The bullet is not a hollow point type but comprises fully hollowed soft lead bullet 12 filled with a very hard and brittle polymer 70 that fragments into sharp pieces upon impact. According to the bullet manufacturer, the polymer employed is a blend of polyaniline, a high molecular-weight polymer, and carbon-based filaments called “cyanate whiskers.” This reference teaches away from the invention disclosed herein.

All the former designs are hollow point bullets that expand while penetrating liquid targets but none comply with the following requirements: preventing the hollow point of a bullet from clogging with debris from intermediate targets; increasing expansion during the perforation of hard materials; preventing the expansion of training bullets during the penetration of liquid targets; and allowing users to identify different cartridge designs that would otherwise have an identical external appearance.

U.S. Pat. Nos. 6,178,890 and 6,305,292, which patents were both issued to Burczinzky, propose a solution to the problem of the cavity in a bullet being filled with debris. In these designs, the bullet is jacketed at the bullet's closed forward end and open at its rear end. This jacket construction is similar to the conventional full metal jacket as specified by NATO, shown in FIG. 14. The jacket is closed at the bullet's nose 28 but open at the rear to allow the introduction of a lead core. The lead core is retained by crimped portion 80.

In the Burczinsky invention, the lead core does not completely fill the jacket, leaving an empty space in the nose that is filled with a polymer. The bullet nose is also provided with axial slits that weaken the jacket's nose and permit expansion. When the bullet strikes a barrier or the target, the nose is compressed axially, thereby expanding the jacket at the nose. Debris produced after intermediate barriers have been perforated have no effect on bullet expansion as there is no open cavity at forward end of the bullet to be clogged. In that these designs have a jacketed (closed) forward end and 28 open rear end 64, they cannot be confused with designs that comprise an open forward end or a hollow point.

The Burczinsky invention promotes bullet expansion during the penetration of a wide variety of target types. It also prevents the bullet from clogging with debris from intermediate targets because bullets of the Burczinsky design do not have a front open cavity. Notwith-standing these characteristics, it cannot be employed to produce a non-expanding hollow point bullet for training purposes nor does it allow for identification of different cartridge types.

Background art bullet manufacturing machines perform necessary bullet-fabrication unit operations in a continuous sequence. The production rate for conventional industrial machines is from one to two bullets per second. What is needed is a device for filling the cavity of a hollow point bullet with an elastomer or a rigid polymer that can be integrated into conventional production machines and achieve commercial production rates.

None of the references and no combination of the references teach techniques that can be used to cause a bullet to produce a large frontal area that fractures after having expanded during the penetration of a liquid target, combining high stopping power with deep penetration, but at much lower velocities than are possible with magnum calibres. None of the references and no combination of the references teaches techniques that can be employed to prevent training hollow point bullets from expanding during the penetration of a liquid target. None of the references and no combination of the references teaches techniques that can be employed to increase the expansion of hollow point bullets during the penetrating of hard targets. Moreover, none of the references and no combination of the references teach how to effectively manufacture an elastomer-filled hollow point bullet or a rigid polymer-filled hollow point bullet.

DISCLOSURE OF INVENTION

The embodiments of the invention disclosed herein achieve one or more of the following purposes: improving, hastening and assuring bullet expansion during the penetration of liquid targets; preventing the hollow point of a bullet from clogging with debris from intermediate targets; increasing bullet expansion during the perforation of hard materials; preventing the expansion of training bullets during the penetration of liquid targets; and allowing users to identify different cartridge designs that would otherwise have an identical external appearance. Another purpose is to provide a technique for designing bullets that achieve these ends.

In one aspect, the invention comprises filling the cavity of a hollow point bullet having an open forward end with a solid substance that transmits pressure throughout its mass as if it were a liquid. Filling of the cavity with such a substance hastens the expansion process and prevents the cavity from filling with debris.

Preferably, the filling is an elastomer that transmits the pressure (e.g., stagnation pressure) applied to the open forward end of the cavity in the bullet (e.g., when the bullet strikes a liquid target or a simulated tissue) to the interior surface of the cavity. The invention is advantageous because it can be employed in all existing hollow point bullets, regardless of the cavity shape, whether the bullet is jacketed or not. Hollow point bullets fitted with the filling of the invention disclosed herein are unaffected by the penetration of intermediate barriers that would otherwise fill the hollow point cavity with debris, thus impeding the bullet's expansion. Moreover, thin metal plate penetration can be reduced by combining the approach of filling the cavity with an appropriate elastomer with modification of other ammunition features, such as bullet shape and velocity. The invention provides much better performance than similar ammunition, in terms of cost, stopping power, penetration depth and metal plate perforation performance.

In a preferred embodiment, the invention is a bullet comprising: a bullet body having a cavity in its forward end that is open at that end and an elastomer filling situated within said cavity. Preferably, the elastomer filling comprises a two-component silicon elastomer. In a preferred embodiment, the elastomer filling has Shore hardness in the range from about 6 to about 90. Preferably, the elastomer filling is vulcanized. More preferably, the vulcanized elastomer filling has a Shore hardness in the range from about 6 to about 90. More preferably, the vulcanized elastomer filling has a Shore A harness of about 70. Preferably, the elastomer is colored, i.e., the elastomer is not clear, but rather a color such as red, green or yellow, etc.

In a preferred embodiment, the bottom of the cavity is rounded or non-planar. In another preferred embodiment the bottom of the cavity is square or flat. In yet another preferred embodiment, the cavity has axial grooves. In a further embodiment, the elastomer filling is a plug having axial grooves or axial holes.

In a preferred embodiment, the elastomer filling is formed into a cylindrical insert before it is inserted in the cavity. Preferably, the insert is exposed to lubricant that can be absorbed by the filling after it is forced into the cavity. Preferably, the elastomer filling is a vulcanizible elastomer that is poured into the cavity before it is vulcanized. In a preferred embodiment, the elastomer filling comprises a thermoplastic that is injected into the cavity. In a preferred embodiment, the elastomer filling is operative to transmit stagnation pressure to the walls of the cavity when the bullet strikes a liquid target. In another preferred embodiment, the elastomer filling is operative to flatten and convert axial forces into radial forces that contribute to bullet expansion when the bullet strikes a hard target.

In another preferred embodiment, the invention is a bullet body having a cavity in its forward end that is open at that end and an elastomer filling situated within said cavity, wherein the characteristics of the bullet are indicated by the color of the elastomer filling, said color being visible at the nose of the bullet.

In another preferred embodiment, the invention is a training bullet comprising: a bullet body having a cavity in its forward end that is open at that end and a rigid polymer filling situated within said cavity, wherein said filling is operative to cause the bullet to have the same ballistic features as a bullet having an elastomer filling of approximately the same size and is operative to prevent the bullet from expanding during penetration of a liquid target. Preferably, the rigid polymer filling is colored. In a further embodiment, the rigid polymer filling is a plug having axial grooves or axial holes. Preferably, the rigid polymer filling has the same density as the elastomer filling that is used in the non-training version of the bullet.

In another preferred embodiment, the invention is a bullet body having a cavity in its forward nose end that is open at that end and a plug compressed within said cavity by swaging or crimping said nose. Preferably, the plug has a loose fit in the cavity prior to being compressed in the cavity by swaging or crimping.

In another preferred embodiment, the invention is a cartridge comprising: a cartridge case containing the bullet disclosed herein, a powder charge or load and a primer.

In another preferred embodiment, the invention is a bullet having an unjacketed, flat nose comprising: a metal body having a hollow point that is filled with an elastomer.

In another preferred embodiment, the invention is a bullet comprising: a generally cylindrical, metal body portion having a longitudinal axis and a first axial cavity portion disposed along the longitudinal axis; a metal nose portion disposed forwardly of said body portion, said nose portion having an unjacketed forward end and a second axial cavity portion disposed along the longitudinal axis; and a generally cylindrical elastomer filling situated within the axial cavity portions, said elastomer filling having a generally flat or slightly convex forward end.

In another preferred embodiment, the invention is a bullet comprising: a metal body having a generally cylindrical portion and a frontal portion having a first longitudinal cavity part; and an elastomer portion, at least a first part of which is disposed in the first cavity part, the elastomer portion having a generally flat, unjacketed forward end. In some embodiments, the cylindrical portion and the frontal portion are also unjacketed. In some embodiments, the generally cylindrical portion has a second longitudinal cavity part in which a second part of the elastomer portion is also disposed. In some embodiments, the tip of the frontal portion has a smaller diameter than the diameter of the cylindrical portion.

In another preferred embodiment, the invention is an adequate penetration, optimum expansion bullet for use against barriers of soft to medium-hardness comprising: a jacket formed of a malleable metal and having a generally cylindrical sidewall, a nose portion disposed forwardly of said cylindrical sidewall, an open forward end, and a rear end portion; said nose portion having a nose-defining wall extending between said cylindrical wall and said open forward end; an elastomer core disposed in part at least within said nose-defining wall; and a metal core seated behind said elastomer core and within said generally cylindrical sidewall in close-fitting relation and extending rearwardly to a position adjacent said rear end portion of said generally cylindrical jacket sidewall.

In another preferred embodiment, the invention is a projectile comprising: a metal body having a generally cylindrical portion and a frontal portion, both the cylindrical portion and the frontal portion having a longitudinal cavity having walls; and an elastomer portion that is disposed in the cavity, the elastomer portion having a generally flat, unjacketed forward end and being operative to transmit a stagnation pressure that is exerted upon the forward end when the projectile strikes a barriers to the walls of the cavity.

In another preferred embodiment, the invention is a bullet comprising: a metal body having an open cavity in its forward end, the cavity having walls, and means for transmitting a stagnation pressure that is exerted upon the forward end when the bullet strikes liquid barriers to the walls of the cavity.

In another preferred embodiment, the invention is a process for making an improved bullet comprising: filling a cavity in a bullet having a flat front end with an elastomer plug, the plug having a flat forward end that ends in the approximately same plane as the front end. Preferably, the filling step involves placing a thermoplastic elastomer plug into a hollow point bullet.

In another preferred embodiment, the invention is a process for making an improved bullet comprising: filling a cavity in a bullet having a nose with a plug and then swaging or crimping the nose. Preferably, the plug has a loose fit with the cavity prior to the swaging or crimping step.

In a further preferred embodiment, the invention is an apparatus and a process for producing the bullets disclosed herein. Preferably, the apparatus for inserting an elastomer into a cavity in a bullet comprises: a table for supporting a bullet; a rotary plate having a plurality of holes along its periphery that are operative to accept a segment of cord, said plate being rotatably connected to the table and being capable of shearing off said segment of cord during its rotation; and an elastomer cord feeding device having a cord feeding device bushing that situated adjacent to the rotary plate and through which the cord feeding device is capable of feeding cord into each hole in the rotary table; and a punch having a punch bushing that situated adjacent to the rotary plate and through which the punch is operative to push the sheared segment of cord into the cavity in the bullet.

In another preferred embodiment, the invention is another apparatus for inserting an elastomer into a cavity in a bullet comprising: a table for supporting a bullet; a reciprocating feeder having a hole in one end that is operative to accept a segment of cord, said feeder being slidably connected to the table and being capable of shearing off said segment of cord during its backward movement; and an elastomer cord feeding device having a cord feeding device bushing that situated adjacent to the reciprocating feeder and through which the cord feeding device is capable of feeding cord into the hole in the reciprocating feeder and pushing the sheared segment of cord into the cavity in the bullet when the feeder is in the forward position.

Further aspects of the invention will become apparent from consideration of the drawings and the ensuing description of preferred embodiments of the invention. A person skilled in the art will realize that other embodiments of the invention are possible and that the details of the invention can be modified in a number of respects, all without departing from the concept. Thus, the following drawings and description are to be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF DRAWINGS

The features of the invention will be better understood by reference to the accompanying drawings which illustrate presently preferred embodiments of the invention. In the drawings:

FIG. 1 is an elevation view of a handgun bullet.

FIG. 2 is an elevation view of a soft tip bullet.

FIG. 3 is a cross-sectional view of a soft tip bullet.

FIG. 4 is an elevation view of an expanded soft tip bullet.

FIG. 5 is a cross-sectional view of a conventional hollow point bullet.

FIG. 6 is a cross-sectional view of an expanded conventional hollow point bullet.

FIG. 7 is a cross-sectional view of an alternative hollow point bullet.

FIG. 8 is a cross-sectional view of an expanded alternative hollow point bullet.

FIG. 9 is a plot of stagnation pressure versus bullet velocity.

FIG. 10 is a cross-sectional view of a conventional full lead hollow point bullet.

FIG. 11 is a cross-sectional view of a conventional jacketed hollow point bullet.

FIG. 12 is an elevation view of a jacketed hollow point bullet showing nose slits.

FIG. 13 shows a cross-sectional view of a bullet employed in Rhino-Ammo™.

FIG. 14 is a cross-sectional view of a conventional full metal case bullet.

FIG. 15 is a cross-sectional view of a preferred embodiment of the invention.

FIG. 16 is a time-lapse illustration of a conventional hollow point bullet penetrating a liquid target.

FIG. 17 is a time-lapse illustration of a hollow point bullet that has been improved in accordance with a preferred embodiment of the present invention penetrating a liquid target.

FIG. 18 is a time-lapse illustration of the first stages of a high velocity, hollow point, hand gun bullet penetrating a thin metal plate.

FIG. 19 is a time-lapse illustration of a high velocity conventional hand gun bullet penetrating a thin metal plate.

FIG. 20 is a time-lapse illustration of the first stages of a high velocity, hollow point, elastomer-filled, hand gun bullet penetrating a thin metal plate.

FIG. 21 is a time-lapse illustration of a low velocity, conventional hand gun bullet penetrating a thin metal plate.

FIG. 22 is a time-lapse illustration of a low velocity, elastomer-filled, hollow point hand gun bullet penetrating a thin metal plate.

FIG. 23 is a cross-sectional view of a bullet and a filling plug with air bleeding grooves in accordance with a preferred embodiment of the invention.

FIG. 24 is a cross-sectional view of the bullet of FIG. 23 with the filling plug inserted.

FIGS. 25A and 25B are cross-sectional views of a bullet with a plain filling plug and bleeding grooves in the cavity wall in accordance with a preferred embodiment of the invention.

FIGS. 26A and 26B are cross-sectional views of a jacketed bullet prepared to receive an elastomer plug in accordance with a preferred embodiment of the invention.

FIGS. 27A and 27B are cross-sectional views of a jacketed bullet showing a stress raiser and a plug ready to be inserted in accordance with a preferred embodiment of the invention.

FIGS. 28A and 28B are cross-sectional views of a jacketed bullet with a stress raiser and the plug inserted in accordance with a preferred embodiment of the invention.

FIGS. 29A and 29B are cross-sectional views of the bullet of FIG. 28 after the nose has been swaged.

FIG. 30 is a cross-sectional view of a jacketed bullet with an annular stress raiser in accordance with a preferred embodiment of the invention.

FIG. 31 is a cross-sectional view of a jacketed bullet with the stress raiser forming tool inserted in the cavity raiser in accordance with a preferred embodiment of the invention.

FIGS. 32A and 32B are cross sectional views of a stress raiser forming tool in accordance with a preferred embodiment of the invention.

FIG. 33 is a cross sectional view of a counter-tapered cavity being filled with a polymerizing elastomer in accordance with a preferred embodiment of the invention.

FIG. 34 is a cross-sectional view of a cartridge of a preferred embodiment of the invention disclosing the position of the center of gravity and the dimensions of the powder load chamber.

FIG. 35 is a cross-sectional view of the cartridge of FIG. 34 with a plain bullet.

FIG. 36 is a cross-sectional view of the cartridge of FIG. 34 with a lighter bullet.

FIG. 37 is a cross-sectional view of the cartridge of FIG. 34 with a bullet having a concave base.

FIG. 38 is a cross-sectional view of the cartridge of FIG. 34 with a cavity filled with a rigid polymer in accordance with a preferred embodiment of the invention.

FIG. 39 is a cross-sectional view of a preferred embodiment of the invention with a very heavy bullet relative to the bullet of FIG. 40.

FIG. 40 is a cross-sectional view of a preferred embodiment of the invention with a lighter bullet relative to the bullet of FIG. 39.

FIG. 41 is an elevation view of a plug feeding machine having a rotary plug holder in accordance with a preferred embodiment of the invention.

FIG. 42 is a cross-sectional view of a plug feeding machine showing a plug ready to be punched into a cavity in a bullet in accordance with a preferred embodiment of the invention.

FIG. 43 is a cross-sectional view a plug feeding machine with a plug inserted into a cavity in the bullet in accordance with a preferred embodiment of the invention.

FIG. 44 is a plan view of a reciprocating plug feeding machine with a reciprocating plug holder in the rear (back) position in accordance with a preferred embodiment of the invention.

FIG. 45 is a plan view of a reciprocating plug feeding machine with a reciprocating plug holder in the forward position in accordance with a preferred embodiment of the invention.

FIG. 46 is a plan view of a reciprocating plug feeding machine with a reciprocating plug holder in the forward position in accordance with a preferred embodiment of the invention.

FIG. 47 is a cross-sectional view a reciprocating plug feeding machine with a plug sheared by the holder in accordance with a preferred embodiment of the invention.

FIG. 48 is a cross-sectional view a reciprocating plug feeding machine showing the sheared plug ready to be inserted into the bullet cavity in accordance with a preferred embodiment of the invention.

FIG. 49 is a cross-sectional view a reciprocating plug feeding machine showing the sheared plug pushed in the bullet's cavity by the cord in accordance with a preferred embodiment of the invention.

The following reference numerals are used to indicate the parts and environment of the invention on the drawings:

-   -   12 soft lead bullet, lead core, bullet body     -   14 soft lead tip     -   18 grooved cavity, cavity with axial grooves     -   20 cavity, empty cavity     -   22 hemispherical hollow point cavity, cavity with round bottom     -   24 bullet jacket, partial jacket, stamped jacket, jacket     -   28 nose portion, nose region, nose, forward end     -   30 closed cavity end, cavity bottom, bottom     -   38 target, final target, liquid target     -   40 hollow point bullet     -   41 improved hollow point bullet, bullet with plug inserted     -   42 elastomer filling, filling, compressed elastomer filling     -   44 initial position, position prior to entry     -   46 cavity filling completed position, cavity filled position     -   48 expansion initiation position     -   50 continuing expansion position     -   52 maximum expansion position     -   54 fragmentation position     -   56 expanded ring, ring     -   58 fragments     -   60 stump     -   62 axial pressure     -   64 open rear end     -   70 brittle polymer     -   74 slits, axial slits     -   75 axial grooves     -   80 crimped portion     -   88 plain cylindrical plug, cylindrical plug, plug     -   90 plug with axial grooves     -   94 polymerizing elastomer     -   96 copper cladding     -   97 case, casing     -   100 powder filling space, standard powder load     -   102 smaller powder space, reduced powder load     -   106 thin plate, plate     -   108 plain bullet     -   110 riveted bullet     -   112 bulge     -   114 thinner side     -   118 hole     -   120 fracture     -   122 fractured cap     -   124 hollow point bullet with riveted nose     -   126 riveted elastomer-filled nose     -   130 sheared plug     -   131 deformed bullet     -   132 large diameter bulge     -   134 radial cracks     -   136 irregular perforation     -   138 table     -   139 holes     -   140 rotary plate, rotating plug holder, plate     -   142 feeding device bushing     -   144 punch busing, bushing     -   146 punch     -   150 extruded cord, cord     -   152 cord feeding device     -   154 reciprocating feeder, feeder     -   158 first prototype bullet     -   160 second prototype bullet     -   162 center of gravity     -   164 mushroom shape     -   166 stress raisers, axial stress raisers     -   168 annular stress raiser     -   170 stress raiser forming tool     -   172 expanding mandrel     -   173 annular lip     -   174 conical end     -   176 radial cuts

MODES FOR CARRYING OUT THE INVENTION

Referring to FIG. 15, a preferred embodiment of the invention is illustrated. In this embodiment, the bullet comprises bullet body 12 having cavity 20 in the nose 28 that is open at the cavity's forward end, filling 88 situated within cavity 20 and partial jacket 24. Preferably, filling 88 is either a colored synthetic elastomer compound with a Shore hardness of about 70 or a colored rigid polymer filling (such as an ethylene copolymer), depending on whether an expanding or a non-expanding hollow point bullet is desired.

Referring to FIG. 17, the progressive expansion of improved hollow point bullet 41 with elastomer filling 42 in cavity 20 is illustrated in initial position 44 just prior to penetrate liquid target 38 at a velocity of about 350 m/sec. Because hollow point cavity 20 is already filled at initial position 44, the stagnation pressure is applied to elastomer filling 42 as soon as it strikes target 38.

After traveling about ten mm, expansion starts at expansion initiation position 48. After traveling about ten mm more, the expansion of improved hollow point bullet 41 reaches a maximum value at maximum expansion position 52, after a total travel in liquid target 38 of about 40 mm. Axial pressure 62 simultaneously expands bullet 41 and bends ring 56 backwards.

At maximum expansion position 52, the velocity of improved hollow point bullet 41 is reduced to about 300 m/sec. This velocity is about 30 m/sec higher than it would have been had improved hollow point bullet 41 had an empty cavity as was the case for conventional hollow point bullet 40 in FIG. 16. Because stopping power is related to the maximum pressure wave intensity that in turn is related to the square of the bullet's velocity, the stopping power of improved hollow point bullet 41 is increased significantly over that of conventional hollow point bullet 40.

With a striking velocity of 350 m/sec it is very difficult to disintegrate the expanded ring of a conventional hollow point bullet. Because the improvements disclosed herein also act as an expansion booster, it is possible to increase the ring's diameter until it disintegrates at fragmentation position 54 to produce fragments 58. At fragmentation position 54, stump 60 remains, with a diameter close to the original caliber and with a velocity close to the 300 m/sec attained at maximum expansion position 52.

As penetration in liquid targets is inversely related to bullet diameter and directly related to the bullet mass, at fragmentation position 54, the bullet has lost about 20 percent of its original mass but its diameter has been reduced by 50 percent. This is why the smaller diameter stump 60 achieves a much deeper penetration into target 38 than if the expanded bullet did not fragment. As illustrated in FIG. 30, if the fracture of expanded ring 56 is sought and bullet's velocity is insufficient to cause fragmentation to occur, fracture can be induced by forming an annular stress raiser 168 at the cavity's bottom.

Comparing the bullet's effect on a testing media, it is noticeable that with the elastomer filled hollow point bullet of the disclosed invention, expansion begins immediately after striking an intermediate barrier and the transitory cavity produced is larger. If expanded ring 56 disintegrates, stump 60 retains about eighty percent of the original bullet's weight and has a much deeper penetration into the target than a similar but conventional unfilled hollow point bullet.

Moreover, if the elastomer filled bullet of the disclosed invention strikes an intermediate barrier, debris does not fill the cavity. If, after striking intermediate barriers, it strikes a liquid target, expansion begins immediately and is more regular than if the cavity were empty.

The disclosed invention can be used to improve all hollow point bullet designs, including those described U.S. Pat. Nos. 219,840; 3,348,486; 3,357,357; 3,911,820; 4,338,862; 4,550,662; 4,947,755; 5,208,224; 5,365,853; 5,454,325; 5,763,819; 5,943,749; 6,115,894; 6,176,186; and 6,178,890; the disclosures of which patents are incorporated by reference as if fully set forth herein. In all cases, the bullet becomes immune to the effect of striking intermediate barriers. Furthermore, expansion begins sooner, increasing pressure wave intensity.

Depending on the original design of the bullet being improved in accordance with the invention disclosed herein, expansion may also be increased. This is not always the case: for example, when a Silver Tip® bullet made in accordance with U.S Pat. No. 4,193,348, is improved in accordance with the invention disclosed herein, the bullet becomes unaffected by intermediate barriers but other performance criteria, such as maximum pressure wave intensity and thin plate perforation, remain unchanged. Furthermore, when the invention disclosed herein is applied in a completely new bullet design, a more efficient bullet can be produced.

While a hollow point bullet cavity having an open forward end is not a closed container, Pascal's principle can be applied when the bullet strikes a liquid target because, at high velocity, all of the liquid inside the cavity is submitted to the stagnation pressure that is applied through the open forward end of the bullet and is consequently transmitted to the walls of the cavity.

The larger expansion and particularly the higher pressure wave generated by elastomer filled hollow point bullets during the penetration of liquid targets is explained by the bullet's higher velocity at the moment full expansion is reached. The effects of the elastomer being placed in the hollow point cavity are different when the bullet strikes hard targets (such as thin metal plates or glass). While an empty hollow point has no effect on bullet expansion when the bullet strikes a thin metal plate, the presence of an elastomer filling has a strong positive effect.

Perforation of thin plate 106 by a high velocity hollow point elastomer filled bullet is illustrated in FIG. 20. Riveting forces flatten elastomer filling 42 to produce riveted elastomer-filled nose 126 and convert the axial forces into radial ones that contribute to bullet expansion. In spite of the riveting, filling 42 is retained and the hollow point is not closed. The riveted diameter is about ten percent larger than an unfilled hollow point and twenty percent larger than a plain (solid) bullet.

Different materials have different effects when used for filling an open forward-end cavity in a bullet. Solids, either crystallized or powdered, transmit the pressure in the same direction as it is applied (e.g., axially, in the case of a bullet) without affecting the walls of the cavity. Consequently, solids such as rigid polymers are preferably employed if a hollow point bullet is not intended to expand during the penetration of liquid targets, as it is the case with training ammunition. If expansion is sought, liquids cannot be employed as a filling, because they are not retained in the open forward-end cavity. High viscosity thixotropic liquids are retained in the cavity but they cause two problems: (1) such liquids gather dirt at the exposed open forward end and (2) expansion is erratic because thixotropic liquids are sometime dispersed at impact. Waxes and soft malleable solids with a Shore hardness below 30 behave like elastomers but only within a limited temperature range: (1) if the temperature is too high, such solids become liquids and flow out of the open forward-end cavity and (2) if the temperature is too low they crystallize or harden and behave like solids.

Elastomers are the preferred solid and stable materials that transmit the pressure according to Pascal's principle, but these materials have two restrictions. First, the glass transition temperature (the temperature at which the elastomer begins to behave like a solid) must preferably be below the temperatures encountered in cold climates. For example, fluoroelastomers are preferably not employed because they have a glass transition temperature of about −10° C. Second, the hardness selected for the elastomer is preferably related to the stagnation pressure (see FIG. 9) expected to be encountered in use. If a relatively hard elastomer provides a good expansion at about 1,500 kg/mm², it may be too hard and behave as a solid if the stagnation pressure is only about 500 kg/mm². For most handgun ammunition, which experience stagnation pressures around 750 kg/mm² (corresponding to velocities from 250 to 400 m/sec), Shore hardness values from six to eighty are preferred. In experiments conducted by the inventor with handgun ammunition improved as disclosed herein, the best experimental results were achieved with an elastomer having a Shore hardness of about seventy.

Because hollow point bullets of the same caliber that have different weight, velocity and expansion features and that would otherwise be externally identical can be produced with the techniques disclosed herein, a purpose of this invention is to provide easy identification of different bullet types. This is preferably achieved be employing colored material as the fillings for the hollow point bullets disclosed herein. Many synthetic elastomers and rigid polymers are easily colored. When employed as the filling, they form a visible colored spot, which is easily identified, at the nose of the bullet. If molded plugs are employed, the bullet identification or the manufacturer's logo can be engraved the plug's tip.

Bleeding means are preferably provided to allow the air trapped below the plug to escape during the insertion process. This is particularly important if plugs are inserted at high velocity (e.g., two plugs per second), because the plug insertion time is about 0.10 sec. For this purpose, FIGS. 23 and 24 illustrate plug with axial grooves 90 that can be used to allow for bleeding.

There are several preferred ways to provide air bleeding during plug insertion to produce preferred embodiments of improved bullet 41, which improved bullet 41 offers several advantages over a bullet with a cylindrical cavity and a sliding fit plug. One preferred approach is illustrated in FIGS. 23 and 24. With this approach, longitudinal (axial) grooves are provided on the plug to produce plug with axial grooves 90. The grooves can be formed on extruded cord 150. In another approach (not illustrated), one or more longitudinal holes are formed in the extruded cord. Because it is difficult to produce very small diameter holes in an extruded cord, producing grooves is preferred. Another approach is illustrated in FIG. 25. With this approach, a plain (ungrooved) cylindrical plug 88 is employed and groves 75 are formed in the cavity's wall to produce cavity with axial grooves 18. These approaches are better suited to rigid poymer plugs that are preferably retained by forming crimped portion 80 at the cavity's edge as illustrated in FIG. 24.

Providing plug with axial grooves 90 is a preferred solution as the grooves can be formed in the extruded cord employed with the filling machines disclosed herein. An alternative solution (not illustrated) is to provide an axial hole in the plug. Another alternative, illustrated in FIG. 25, is to provide grooved cavity 18 having axial grooves 75. In this case, a plain cylindrical plug 88 (i.e., one with no grooves) may be employed. If grooves are used for air bleeding, the plug preferably has a sliding fit in the hole. It can be easily retained by crimping the edge of the cavity. This is not a preferred approach for elastomer plugs as crimping reduces bullet expansion. Instead, it is a preferred way to produce a non-expanding hollow point bullet having a rigid polymer filling.

A more preferred approach which is better suited to elastomer plugs is illustrated in FIGS. 26A and B through 29A and B. Preferably, with this approach, a large clearance is left between plain plug 88 and the sidewall of cavity 20. With the appropriate clearance, satisfactory air bleeding can be achieved. When bullet nose 28 is swaged, shown in FIG. 29 as a subsequent operation, cylindrical plug 88 is compressed and completely fills cavity 20 regardless of the shape of cavity 20 or whether grooves have been formed on the walls of cavity.

In this embodiment, cylindrical plug 88 has a smaller diameter than cavity 20 to allow for air to escape through the annual space between the outer walls of plug 88 and the inner walls of cavity 20. The required volume of plug 88 is that necessary to fill cavity 20 when the full nose has been swaged as in FIGS. 29A and B. In this embodiment, it is possible to employ a cavity with a rounded bottom that helps prevent the expanded bullet from breaking up when full expansion has been reached.

As illustrated in FIG. 33, if the shape of cavity 84 is other than cylindrical, cavity 84 is preferably filled with polymerising elastomer 94 which is deposited in cavity 84 in the liquid state and then polymerized. While the approach of filling a cavity in a bullet with a polymerizing elastomer (as indicated in FIG. 33) is technically feasible, it is not preferred because it is not a convenient approach and because polymerizing elastomers can be expensive. With this approach, the elastomer is applied with an automatic dosing machine. Such machines can be complicated to maintain. In addition, a curing oven must be introduced into the production line to cure the elastomer.

An alternative approach, injecting a thermoplastic elastomer into a bullet cavity, is also not preferred because it is a relatively slow and expensive process. With this approach, the bullet must be placed into an injection mold and the associated unit processes (e.g., from feeding the mold to injecting the elastomer) are relatively slow. Use of an injection molding machine is, therefore, a relatively expensive approach, particularly considering the slow output of such machines when filling bullets.

In the background art bullets illustrated in FIGS. 11 and 12, stamped jacket 24 resists expansion, even though it is thinner at the nose; Slits 74 can be formed prior to the core insertion to allow the jacket to shred upon the bullet's expansion. If the bullet is copper clad, as shown in FIGS. 26A and B, copper cladding 96 has a uniform thickness and slits can not be made prior to insertion of lead core 12. Axial stress raisers 166, shown in FIGS. 27A and B must be cut through the bullet nose to allow and control expansion. Once plug 88 is inserted, as illustrated in FIGS. 28A and B, nose 20 is swaged as shown in FIGS. 29A and B. Swaging compresses plug 88 to form elastomer filling 42 and closes the gap in stress raisers 166. Axial stress raiser technology is disclosed in U.S. Pat. No. 219,840 issued to Winchester, the disclosure of which patent is incorporated by reference as if fully set forth herein.

If fracture of expanded ring 56 is sought but bullet velocity is insufficient, fracture can be induced as illustrated in FIG. 30, forming annular stress raiser 168 at the bottom of cavity 20. For this purpose, annular stress raiser forming tool 170, illustrated in FIG. 31, is preferably introduced into cavity 20. As shown in FIGS. 32A and B, stress raiser forming tool 170 is formed by expanding mandrel 172 having annular lip 173. A shaft with conical end 174 is pulled upon, opening the mandrel and forming internal annular stress raiser 168. Radial cuts 176 allow the mandrel to open.

When a shooter is preparing to employ specialized ammunition such as the elastomer-filled hollow point bullets disclosed herein, he usually trains with a simpler and less expensive version called training ammunition. Training ammunition must have the same recoil and trajectory as the specialized ammunition. The powder loads must be identical and must leave the same empty space bellow the bullet. The bullet also must have the same dimensions, weight and position of its center of gravity.

For training purposes, there is a need for non-expanding bullet ammunition that duplicates the recoil and the external ballistic features of a particular hollow point bullet, assuring the same point of impact as that particular hollow point bullet. Recoil is related to bullet weight and powder load and is easily duplicated from one cartridge to another. External ballistics is related to bullet shape and the location of its center of gravity that cannot be duplicated with full non-hollow point bullets.

The problem of constructing non-expanding training bullets is illustrated in FIGS. 34 through 38. FIG. 34 illustrates a hollow point bullet with a hollow point cavity that is filled with elastomer filling 42. Center of gravity 162 is slightly below cavity bottom 30. FIG. 35 illustrates the bullet of FIG. 34 with the cavity removed: the weight of the bullet is higher and center of gravity 162 is moved toward the bullet's tip. FIG. 36 illustrates the bullet of FIG. 34, shortened to achieve the same weight as the bullet of FIG. 34. Center of gravity 162 is displaced forward and powder filling space 100 in case 97 is enlarged, modifying the powder combustion rate. FIG. 37 illustrates a bullet with a hollow base to maintain its exterior dimensions and weight unchanged. Center of gravity 162 is moved forward and powder filling space 100 in case 97 is enlarged. A preferred solution to achieving unchanged ballistic performance for a non-expanding training bullet when a bullet filling is used is to replace elastomer filling 42 with rigid polymer filling 70 having the same density as the elastomer filling, as illustrated in FIG. 38.

In a preferred embodiment illustrated in FIG. 29, an elastomer-filled hollow point bullet is produced by compressing elastomer plug 42 within the cavity by swaging the bullet's nose. This is not possible when a rigid polymer plug is used as the filling. Instead, a preferred solution is that illustrated in FIGS. 24 and 25A and B, in which, instead of an elastomer plug, a rigid polymer plug is employed. Polymer plug 90 can be formed with the plug filling machines disclosed herein by employing an extruded polymer cord as a starting material. As illustrated in FIG. 24, its installation requires formation of crimped portion 80 of the nose of the bullet to hold it in position. Because hollow point bullets with different cavity fillings or having different weights, velocities look alike, the cavity filling is preferably colored to allow for easy differentiation.

As illustrated in FIGS. 26A and B through 29A and B, if plug 88 has a sliding fit with larger cylindrical cavity 20, it must be retained in position by swaging or compressing the bullet's nose forward end. The forward end of cavity 20 remains open after the swaging step.

The bullet-cavity filling approaches illustrated in FIGS. 23 to 29A and B are very economical, if instead of employing a (relatively expensive) pre-molded elastomer plug, the plugs are cut from an elastomer cord. Thus, a preferred approach is to provide a device that not only cuts the cord (forming the plugs) but also places each plug in the cavity of a bullet.

Two preferred devices for performing this task are illustrated herein. A person having ordinary skill in the art of bullet production would understand how to incorporate the devices disclosed herein into a bullet production machine and would understand that other approaches are possible.

A first preferred device employs a rotary feeder and is illustrated in FIGS. 41-43. The device is preferably comprised of indexed rotary plate or plug holder 140 that turns over fixed table 138. Rotary plate 140 contains numerous holes 139, each with a depth equal to the elastomer plug length. At the left, cord feeding device 152 pushes exactly the length of elastomer cord 150 necessary to form a plug through feeding device bushing 142 and into one of the holes 139. When rotary plate 140 turns, cord 150 is sheared between rotary plate 140 and feeding device bushing 142, forming sheared plug 88 that is retained in one of the holes 139. As plate 140 rotates, each plug is conveyed to a position that is in line with the axis of punch 146 and punch bushing 144. Along the same axis, the centerline of empty cavity 20 in a bullet is indexed below sheared plug 88. Downward movement of punch 146 through punch bushing 144 forces sheared plug 88 into empty cavity 20, filling the cavity 20 and producing bullet with plug inserted 41. Bullets move along table 138 in direction A as illustrated in FIG. 41.

Rotating plug holder 140 stops at each of the holes 139 to allow, at one side, feeding of cord 150 by cord-feeding device 152, and, at the opposite side, driving of sheared plug 88 into empty cavity 20 by punch 146. When punch 146 returns to his initial (up) position, plate 140 turns one increment. The feeding cycle requires accelerating and stopping of plate 140 at a preferred rate of about 0.5 sec per cycle.

A second preferred device employs a reciprocating feeder (or shuttle) as illustrated in FIGS. 44-49. The device is comprised of reciprocating feeder 154 that slides over table 138. Reciprocating feeder 154 has a single hole and a preferred sliding movement of about 5 mm for a 3.5 mm diameter plug. Cord feeding device 152 pushes exactly the length of cord 150 necessary to form a plug through bushing 144 into feeder 154. Sheared plug 130 that was formed during a previous, backward movement of reciprocating feeder 154 (see FIG. 47) is situated above (see FIG. 47) empty cavity 20. Cord feeding device 152 (see FIG. 49) pushes sheared plug 130 into cavity 20. In this way, the plug 88 is inserted in the bullet.

With the reciprocating feeder approach, sheared plug 130 preferably has a sliding fit in the cavity in the bullet. To retain inserted plug 88, a second operation is performed in a different machine to produce a light crimping in the top of the bullet cavity, as is illustrated in FIG. 29. The advantage of the reciprocating feeder approach is that inertial forces are lower than with the rotary feeder approach, allowing a faster operation.

Forming plug 130 from extruded cord 150 and fitting it simultaneously in a hollow point bullet with the machine illustrated in FIGS. 41 through 49 is a simple, inexpensive and rapid procedure. However, fitting a plug into a cavity with which it has a diametrical interference or even a sliding fit is difficult because air trapped below the plug can make plug introduction difficult. Consequently, air bleeding must be provided. Moreover, the rotary feeder illustrated in FIGS. 41 through 43 uses punch 146 to drive sheared plug 130, but with the reciprocating feeder illustrated in FIGS. 44 through 49, the force that drives the plug into the cavity is limited, as it must be exerted by cord 150. For this reason, with the reciprocating feeder, plug 130 must have a sliding fit in cavity 20. As plug 130 is inserted at a very high velocity, in about 0.17 sec., ample air bleeding must be provided.

The shape of the bottom of cavity 20 influences the disintegration of expanded ring 56. For some applications, an expanded ring that expands and then disintegrates is a sought-after feature. If the bottom of cavity 20 is flat, as shown in FIG. 23, the sharp edge at the intersection of the flat cavity bottom and cavity wall concentrates stresses during expansion, promoting the fracture and disintegration of expanded ring 56. If the sharp edge at the bottom of the cavity is removed by making the bottom rounded of hemispherical as shown in FIG. 34, disintegration of expanded ring 56 may be avoided.

A more preferred embodiment of the invention has a number of characteristics. Preferably, it comprises a loose-fitting cylindrical elastomer plug that is formed and fitted by a reciprocating machine disclosed herein into a hollow point bullet having a cylindrical cavity and an unfinished nose shape, wherein a finished bullet is achieved by swaging the former bullet to compress the plug inside the cavity.

New bullets can be designed so as to embody the invention disclosed herein. Expansion can be adjusted to achieve the required performance through adjustment of cavity dimensions and the placement and design of stress raisers. Even with low velocities, it is possible to design bullets that fracture after expansion. It is also possible to design bullets that expand but do not fracture, retaining most of the original weight.

WORKING EXAMPLES

Two prototype ammunition designs were developed and tested to illustrate the possibilities of basing a new bullet design on the invention disclosed herein.

One is low penetration ammunition. For home defense, ammunition that is issued to personnel with little training in defense or that is employed in crowded areas should be convenient to use and have the following features: good stopping power, i.e., stopping power equivalent to a military (e.g., NATO) ammunition would be the minimum acceptable; low penetration of intermediate barriers, i.e., although police require high penetration of cars in defensive applications, not only would this feature be unnecessary but it may be a handicap in crowded areas or in home defense applications; and low report, i.e., a loud report like that of a 9 mm NATO round may produce permanent hearing damage, while a report that is three decibels (dB) less would make the report acceptable.

The second is ammunition for police application that must comply with the “INS National Firearm Unit Ballistic Gelatin Test Protocol.” The bullet must comply with several stringent requirements, such as insensibility to intermediate barriers, high stopping power and satisfactory penetration.

Working Example No. 1

Thin metal plate penetration increases with the square power of velocity and decreases with the bullet's frontal surface area. If the only desired feature of a bullet is a low thin metal plate penetration, bullet velocity can be reduced as necessary by reducing the powder load. Automatic pistol ammunition must produce sufficient recoil to operate the slide. Recoil is a linear function of bullet mass and velocity. The maximum bullet mass is limited by the cartridge design. Bullets have a maximum possible length (and mass) limited by the cartridge dimensions, as the assembly cannot exceed a certain length. Comparing FIG. 39 with FIG. 40, it is noticeable in FIG. 39 that the bullet is longer (and heavier) and consequently smaller powder space 102 left in the case bellow the bullet is restricted. A ten percent increment in the bullet's mass would reduce the powder capacity by 50 percent, reducing the kinetic energy by the same amount, and the bullet would not have sufficient impulse to operate an automatic pistol. A balance must be reached between the bullet weight, the powder space and the bullet velocity.

First prototype 9 mm bullet 158 was comprised of a plain lead alloy and had a weight of 11.7 grams. Because no jacket was provided, embodiments of first prototype bullet 158 were either copper clad or Teflon® coated. The hollow point had a cavity that was 3.75 in diameter by 9.5 mm in length before nose swaging and contained compressed elastomer filling 42 in accordance with the invention disclosed herein.

In this example, the bullet had a velocity about 230 m/sec. At this velocity, neither a plain bullet nor a hollow point one expanded while penetrating a thin metal plate or a liquid target. Either bullet, plain or hollow point, penetrated two 0.9 mm steel plates. Calculated stopping power was about 45 percent (too low) and penetration in a liquid target, about 1,200 mm (too much).

Employing a hollow point with a cavity filled with elastomer 42, bullet 158 expanded to fourteen mm after perforating the first plate and denting the second plate. Fired on a liquid target (or testing media), bullet 158 expanded to sixteen mm and penetrated 350 mm. Stopping power was about 65 percent, equivalent to a military bullet. The reduced powder load produced report 3 Db less than military NATO ammunition.

FIG. 22 illustrates the deformation of a thin plate by low velocity elastomer filled hollow point bullet 158. The original hollow point elastomer 42 filling was compressed into lenticular shape within the riveted nose increasing the diameter by 30 percent. As thin plate perforation is an exponential function of the bullet diameter, this increment is sufficient to reduce penetration by half. A heavy (11.7 grams), hollow point 9 mm bullet travelling at 235 m/sec expanded to 13 mm after perforating two consecutive 0.9 mm mild steel plates. The same bullet with the hollow point filled with an elastomer expanded to 17 mm perforating only one plate. Thus, the technique disclosed herein employed with lead low velocity bullets reduced perforation capacity by 50 percent.

A low thin metal plate perforation capacity is a sought-after feature if the ammunition is to be fired in places where excessive thin plate perforation capacity may be a liability. Such places include air plane cabins, homes, banks, nuclear or electrical plants control rooms. Low penetration ammunition is preferably expressly designed for such a purpose and hollow point elastomer filled cavities contribute greatly to the achievement of the required performance

Working Example No. 2

Referring to FIG. 40, another cartridge as a preferred embodiment of the invention is illustrated. In this embodiment, the cartridge comprised powder filling space 100 and second prototype bullet 160 having cavity filled with elastomer 42, both of which were situated in case 97. Second prototype bullet 160 was comprised of a plain lead alloy with six percent antimony and had a weight of 7.5 grams. Because no jacket was provided, embodiments of second prototype bullet 160 were either copper clad or Teflon® coated. The hollow point had a cavity that was 3.75 in diameter by 9.5 mm in length and contained elastomer filling 42 in accordance with the invention disclosed herein.

Upon striking a liquid target at a velocity of 350 m/sec, bullet 160 expanded to sixteen mm, compared to a 12 mm expansion for a Silver Tip® bullet, producing a pressure wave intensity that was 40 percent higher. In that the expanded ring disintegrated after reaching maximum expansion, penetration of second prototype bullet 160 was 440 mm, compared to 200 mm for a Silver Tip® bullet.

Second prototype bullet 160 expanded to 14 mm (or 56 percent) after perforating three No. 20 steel plates. The same bullet without an elastomer filling expanded to 12 mm (or 33 percent), perforating four plates. An unmodified Silver Tip® bullet perforated three such plates.

Compared with all 9 mm ammunitions on the market, the performance of second prototype bullet 160 was vastly superior in the following ways: lower cost (all other ammunitions are jacketed); insensitivity to intermediate barriers; higher stopping power; deeper target penetration; and similar thin plate perforation.

Industrial Applicability

The invention disclosed herein has utility in a variety of applications, including those disclosed herein, and in facilitating the design of more efficient, new hollow point bullets. The invention is capable of improving, hastening and assuring the expansion of bullets during the penetration of liquid targets, preventing the bullet from clogging with debris from intermediate targets, increasing bullet expansion during the perforation of hard materials and identifying with a colored spot or an engraved plug tip different cartridges that would otherwise have an identical external appearance. For training purposes, the invention can be used to prevent hollow point bullets from expanding.

Many variations of the invention will occur to those skilled in the art. Some variations include modification of existing bullets and cartridges. Other variations call for new bullet and cartridge designs. All such variations are intended to be within the scope and spirit of the invention. 

1. A bullet comprising: a metal bullet body having a body diameter and a cavity in its forward end that is open at that end, said cavity having a bottom; and an elastomer filling situated substantially within said cavity; wherein said metal bullet body is operative to expand when the bullet strikes a target.
 2. The bullet of claim 1 wherein the elastomer filling has a cylindrical shape having an elastomer filling diameter.
 3. The bullet of claim 1 wherein the elastomer filling has Shore hardness in the range from about 30 to about
 90. 4. The bullet of claim 2 wherein the elastomer filling diameter is less than half of the body diameter.
 5. The bullet of claim 4 wherein the elastomer filling has at least one axial groove.
 6. The bullet of claim 1 wherein the elastomer filling has a transverse cross-sectional shape that is polygonal.
 7. The bullet of claim 1 wherein the elastomer is colored.
 8. The bullet of claim 1 wherein the bottom of the cavity is rounded or non-planar.
 9. The bullet of claim 1 wherein the bottom of the cavity is square or flat.
 10. The bullet of claim 1 wherein the cavity has at least one axial groove.
 11. The bullet of claim 1 wherein the elastomer filling is a plug having at least one axial element selected from the group consisting of an axial groove and an axial holes.
 12. The bullet of claim 1 wherein the elastomer filling is formed into a cylindrical insert before it is inserted in the cavity.
 13. The bullet of claim 12 wherein the insert is exposed to lubricant that can be absorbed by the filling after it is forced into the cavity.
 14. The bullet of claim 1 wherein the elastomer filling is a vulcanizible elastomer that is poured into the cavity before it is vulcanized.
 15. The bullet of claim 1 wherein the elastomer filling comprises a thermoplastic that is injected into the cavity.
 16. The bullet of claim 1 wherein the elastomer filling is operative to transmit stagnation pressure to the walls of the cavity when the bullet strikes a liquid target.
 17. The bullet of claim 1 wherein the elastomer filling is operative to flatten and convert axial forces into radial forces that contribute to bullet expansion when the bullet strikes a hard target.
 18. The bullet of claim 1 further comprising cladding surrounding said body wherein said cladding and said body have a plurality of axial stress raisers formed therein adjacent to said forward end.
 19. The bullet of claim 1 wherein said forward end is swaged to compress said elastomer filling in said cavity.
 20. The bullet of claim 1 wherein said body has an annular stress raiser formed therein adjacent to the bottom of said cavity.
 21. A projectile comprising: a metal bullet body having a cavity in its forward end that is open at that end and an elastomer filling situated within said cavity, wherein the characteristics of the bullet are indicated by the color of the elastomer filling, said color being visible at the forward end of the bullet.
 22. A training bullet comprising: a bullet body having a cavity in its forward end that is open at that end and an rigid polymer filling situated within said cavity; wherein said filling is operative to cause the bullet to have the same ballistic features as a bullet having an elastomer filling of approximately the same size and is operative to prevent the bullet from expanding during penetration of a liquid target.
 23. The training bullet of claim 22 wherein the rigid polymer filling is colored.
 24. The training bullet of claim 22 wherein the rigid polymer filling is a plug having at least one axial groove or axial hole.
 25. The training bullet of claim 22 wherein the rigid polymer filling has the same density as the elastomer filling that is used in the non-training version of the bullet.
 26. A bullet comprising: a body having a cavity in its forward, nose end that is open at that end; and a plug compressed within said cavity by swaging or crimping said nose.
 27. The bullet of claim 26 wherein the plug has a loose fit in the cavity prior to being compressed in the cavity by swaging or crimping.
 28. A cartridge comprising: a cartridge case containing the bullet of claim 1, a powder charge or load and a primer.
 29. A bullet comprising: a projectile having a metal body having a hollow point that is filled with an elastomer, said projectile having an unjacketed, flat nose.
 30. A bullet comprising: a generally cylindrical, metal body portion having a longitudinal axis and a first axial cavity portion disposed along the longitudinal axis; a metal nose portion disposed forwardly of said body portion, said nose portion having an unjacketed forward end and a second axial cavity portion disposed along the longitudinal axis; and a generally cylindrical elastomer filling situated within the axial cavity portions, said elastomer filling having a generally flat or convex forward end.
 31. A bullet comprising: a metal body having a substantially cylindrical portion and a frontal portion having a first longitudinal cavity part; and an elastomer portion, at least a first part of which is disposed in the first cavity part, the elastomer portion having a substantially flat, unjacketed forward end.
 32. The bullet of claim 31 wherein the cylindrical portion and the frontal portion are also unjacketed.
 33. The bullet of claim 31 wherein the generally cylindrical portion has a second longitudinal cavity part in which a second part of the elastomer portion is also disposed.
 34. The bullet of claim 31 wherein the tip of the frontal portion has a smaller diameter than the diameter of the cylindrical portion.
 35. An adequate penetration, optimum expansion bullet for use against barriers of soft to medium-hardness comprising: a jacket formed of a malleable metal and having a generally cylindrical sidewall, a nose portion disposed forwardly of said cylindrical sidewall, an open forward end, and a rear end portion, said nose portion having a nose-defining wall extending between said cylindrical wall and said open forward end; an elastomer core disposed in part at least within said nose-defining wall; and a metal core seated behind said elastomer core and within said generally cylindrical sidewall in close-fitting relation and extending rearwardly to a position adjacent said rear end portion of said generally cylindrical jacket sidewall.
 36. A projectile comprising: a metal body having a generally cylindrical portion and a frontal portion, both the cylindrical portion and the frontal portion having a longitudinal cavity having walls; and an elastomer portion that is disposed in the cavity, the elastomer portion having a generally flat, unjacketed forward end and being operative to transmit a stagnation pressure that is exerted upon the forward end when the projectile strikes a barriers to the walls of the cavity.
 37. A bullet comprising: a metal body having an open cavity in its forward end, the cavity having walls; and means for transmitting a stagnation pressure to the walls of the cavity when said stagnation pressure is exerted upon the forward end when the bullet strikes a liquid target.
 38. A process for making an improved bullet comprising: filling a cavity in a bullet having a flat front end with an elastomer plug, the plug having approximately the same dimensions as the cavity and a flat forward end that ends in the approximately same plane as the front end.
 39. The process of claim 38 wherein the filling step involves placing a thermoplastic elastomer plug into a hollow point bullet.
 40. A process for making an improved bullet comprising: filling a cavity in a bullet having a nose with a plug; and swaging or crimping the nose.
 41. The process of claim 40 wherein the plug has a loose fit with the cavity prior to the swaging or crimping step.
 42. An apparatus comprising: means for performing the filling step of claim 40; and means for performing the swaging or crimping step of claim
 40. 43. An apparatus for inserting an elastomer into a cavity in a bullet comprising: a table for supporting the bullet; a rotary plate having a plurality of holes along its periphery that are operative to accept a segment of cord, said plate being rotatably connected to the table and being capable of shearing off said segment of cord during its rotation; an elastomer cord feeding device having a cord feeding device bushing that situated adjacent to the rotary plate and through which the cord feeding device is capable of feeding cord into each hole in the rotary table; and a punch having a punch bushing that situated adjacent to the rotary plate and through which the punch is operative to push the sheared segment of cord into the cavity in the bullet.
 44. A process of using the apparatus of claim 43 to produce a bullet comprising an elastomer filled cavity having an open forward end comprising: a step for introducing an elastomer cord to the apparatus of claim 43; and a step for shearing the elastomer cord to produce a plug; and a step for inserting the plug into a cavity of a hollow point bullet.
 45. A bullet comprising an elastomer filled cavity having an open forward end that is produced by the process of claim
 44. 46. An apparatus for inserting an elastomer into a cavity in a bullet comprising: a table for supporting the bullet; a reciprocating feeder having a hole in one end that is operative to accept a segment of cord, said feeder being slidably connected to the table and being capable of shearing off said segment of cord during its backward movement; and an elastomer cord feeding device having a cord feeding device bushing that situated adjacent to the reciprocating feeder and through which the cord feeding device is capable of feeding cord into the hole in the reciprocating feeder and pushing the sheared segment of cord into the cavity in the bullet when the feeder is in the forward position.
 47. A process of using the apparatus of claim 46 to produce a bullet comprising an elastomer filled cavity having an open forward end comprising: a step for introducing an elastomer cord to the apparatus of claim 43; and a step for shearing the elastomer cord to produce a plug; and a step for inserting the plug into a cavity of a hollow point bullet.
 48. A bullet comprising an elastomer filled cavity having an open forward end that is produced by the process of claim
 47. 